1. Field of the Invention
The present invention relates to a master for bluetooth communication and method for establishing a beacon channel thereof, and more particularly, to a master for bluetooth communication and a variable duration beacon channel for controlling parked slaves.
2. Description of the Related Art
Generally, Bluetooth is a wireless communication protocol for transmitting data such as video data within a distance from 10 m to 100 m at a maximum speed of 1 Mbps.
Bluetooth units intercommunicating according to a bluetooth communication method are communicably connected through processes such as Inquiry, Inquiry Scan, Page, and Page Scan. Through these processes, a master and a slave are determined according to a role thereof performed in a network.
When rearranging a connection state of the bluetooth units, the time clock and frequency pattern of the bluetooth units need to be matched to one another.
Among the processes of connecting the bluetooth units, Inquiry is a repetitious frequency transmission of a master to a slave for matching the frequency pattern between the master and slave.
Inquiry Scan is the process of frequency detection and synchronization of the slave.
Page is a clock signal transmission from the master to the slave for matching the time clock between the master and slave. Page Scan is the process of clock signal detection and synchronization of the slave.
A piconet is constructed by the above processes in such a manner that at least one slave is connected to a master.
Conventional bluetooth communication enables intercommunication in a piconet by connecting up to seven slaves to a master in active mode. In order to connect a new slave to the piconet in which seven slaves are actively connected to a master, intermittent connection between the new slave and the master should be guaranteed.
The intermittent connection of the master and slave is called a park mode. By controlling the number of slaves in the park mode (hereinafter, referred to as parked slaves), the number of slaves to be connected to the piconet can be variably controlled.
For example, when a new slave is connected to a piconet in which seven slaves are actively connected to a master, an existing slave in the active mode needs to be parked.
The master establishes a beacon channel between transmission channels at regular intervals, allowing parked slaves to synchronize to the master or request switching to the active mode for their desired communication.
If the beacon channel duration is fixed by a master for maintaining connection with parked slaves, the network is inefficiently used, especially in the piconet environments where the number of parked slaves and the type of Synchronous Connection Oriented (SCO) slaves are varied. That is, when the duration of the beacon channel is fixed at a value longer than the minimum duration necessary for maintaining connection with the then parked slaves, the extra time can not be used for data transmission, resulting in inefficient use of the network.